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TAM-01 showed that a quarter of the usual tamoxifen dose, taken for three years, roughly halved the risk of a new or recurrent breast cancer after treatment for DCIS or other pre-invasive changes, with far fewer of the side effects that make women stop the full dose.
Tamoxifen at 20 mg daily prevents recurrence after ductal carcinoma in situ but hot flushes, endometrial cancer and thrombosis limit its use. TAM-01 was an Italian phase 3 trial that randomised 500 women with breast intraepithelial neoplasia (atypical ductal hyperplasia, lobular carcinoma in situ or oestrogen receptor-positive or unknown ductal carcinoma in situ) to tamoxifen 5 mg daily or placebo for three years. The primary endpoint was the incidence of invasive breast cancer or ductal carcinoma in situ.
Low-dose tamoxifen roughly halved the rate of breast events, including contralateral cancers, with no significant excess of endometrial cancer or venous thrombosis and only a modest increase in hot flushes. The benefit persisted in longer follow-up. Low-dose tamoxifen is now offered as an alternative for women who cannot tolerate the standard dose.
The full inclusion and exclusion criteria are on the registry record. Read 2026-10-07. Recruiting overall does not mean a particular site is open; ask the study team.
ClinicalTrials.gov data courtesy of the US National Library of Medicine.
Shares Ductal carcinoma in situ (DCIS), Tamoxifen, Endocrine therapy (SERMs, AIs, SERDs), Breast cancer (all types) and the tag subtype-trials.
Shares Breast cancer (all types) and the tag subtype-trials.
Shares Breast cancer (all types) and the tag subtype-trials.
Shares Breast cancer (all types) and the tag subtype-trials.
Shares Breast cancer (all types) and the tag subtype-trials.
Shares Breast cancer (all types) and the tag subtype-trials.
Shares Breast cancer (all types) and the tag subtype-trials.
Shares Breast cancer (all types) and the tag subtype-trials.
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